武居 昌宏

In the present study, cross-sectional capacitance is measured in a microchannel with 12 multi-layered electrodes. The cross-sectional capacitances of microparticles of three different diameters are measured upstream and downstream. Based on these measurements, the particle concentration in terms of particle volume fraction is calculated. The particle volume fractions at three configuration areas of electrode pairs, namely, at ones containing adjacent, horizontal, and vertical pairs, are considered for ease of understanding of the particle concentration for different electrode pairs. The particle volume fraction shows an increment of 1.0-9.3% for electrode pairs near the channel walls, but decreased by 0.4-0.96% for center electrode pairs from the upstream cross-section to the downstream cross-section. Moving from the inlets to the outlet, the particles drift away from the center of the microchannel and approach the channel walls and the number of particles that migrate toward the channel walls increases clearly in the outlet area. (C) 2013 Elsevier Ltd. All rights reserved.

In this paper, we present an application of electrical resistance tomography to analyze the formation of thrombosis in blood. Experiments were conducted using bovine blood under thrombogenic conditions. The concentration of red blood cells in the blood was varied to see the cell concentration dependent detection of thrombogenic process. The initial changes in thrombogenic conditions, which are due to change in plasma proteins, were noticed in cell-free condition. But, it was difficult to notice the changes caused by plasma proteinsin the presence of natural level of cell concentration.

現在，植込み型補助人工心臓が開発され，心臓病患者は退院できるまでになっている．しかしながら，補助人工心臓の最大の問題点は血栓の形成であり，患者にとっての命綱は血栓可視化計測システムの存否であるが、未だ実用化されていない．<br>  本研究では，プロセス・トモグラフィー法を用いた血栓可視化計測法の基本コンセプトを提案し，本手法を用いて，静止血液中での様々な種類の血栓を用いて血栓沈降の断面導電率分布の可視化を行った．その結果，血栓がセンサー断面を通過すると，相対電圧が増加した．同時に，平均相対空間導電率が減少し，血栓の中心通過位置を定性的に特定することが出来た．このことから，血栓沈降時の相対空間導電率の減少を検出でき，血栓可視化計測システムの実用化の可能性について示した．

The flow characteristics of a new hybrid vertical axis wind turbine which has advantages of the drag type and the lift type wind turbine have been investigated by the conditional sampling PIV. The experimental apparatus is constructed using the PIV measurement system with a conditional sampling device and a new hybrid vertical axis wind turbine model installed in a circulating water channel. The measured velocity vector fields have clarified that the low velocity regions are inside of rotating turbine and the downstream of it. The influences of the low velocity regions on the torque generated by the blades are investigated by the tangential forces calculated by the pressure distribution around the blades calculated from the velocity fields measured by PIV. And, it has been clarified that the tangential forces of the blades in the low velocity regions are small. Moreover, it has been clarified that the tangential forces generated by the rotating hybrid blades are sourced not only by the lift but also by the drag in the low tip speed ratio case. Therefore, the effectiveness of the hybrid blade for the new vertical axis wind turbine has been demonstrated. © 2013 The Japan Society of Mechanical Engineers.

Active infrared thermography for nondestructive testing and evaluation is a rapidly developing technique for quick and remote inspection of subsurface details of test objects. Sinusoidal modulated thermal wave imaging such as Lock-in thermography (LT) significantly contributed to this field by allowing low power controlled modulated stimulations and phase based subsurface detail extraction capabilities. But demand of repetitive experimentation required for depth scanning of the test object, limits its applicability for realistic applications and demands multi frequency low power stimulations. Non-stationary thermal wave imaging methods such as frequency modulated thermal wave imaging (FMTWI), digitized FMTWI and coded thermal wave imaging methods permitting multi frequency stimulations to cater these needs and facilitate depth scanning of the test object in a single experimentation cycle. This contribution highlights theory, modeling and simulation for non-stationary modulated thermal wave imaging methods for non-destructive characterization of solid materials. © 2013 SPIE.

InfraRed Thermography (IRT) is one of the promising technique for non-destructive testing method for characterization of materials. This technique relies on evaluation of the surface temperature variations to detect the presence of surface and subsurface anomalies within the material. Due to its whole field and remote testing capabilities, IRT has gained significant importance in testing of Glass Fiber Reinforced Plastic (GFRP) materials. A GFRP sample with defects of various sizes at a given depth was inspected using non-stationary thermographic techniques. In order to highlight the defect detection capabilities of the proposed non-stationary schemes, a comparison has been made using matched excitation energy in frequency domain by taking signal to noise ratio into consideration. © 2013 SPIE.

Thermal Wave Detection and Ranging (TWDAR) for non-destructive testing (TNDT) is a whole field, non-contact and non-destructive inspection method to reveal the surface or subsurface anomalies in the test sample, by recording the temperature distribution over it, for a given incident thermal excitation. Present work proposes recent trends in nonstationary thermal imaging methods which can be performed with less peak power heat sources than the widely used conventional pulsed thermographic methods (PT &amp PPT) and in very less time compared to sinusoidal modulated Lockin Thermography (LT). Furthermore, results obtained with various non-stationary thermal imaging techniques are compared with the phase based conventional thermographic techniques. © 2013 SPIE.

Nowadays, fluid flow in a microchannel has emerged as an important area of research. This has been motivated by their various applications such as medical and biomedical use, computer chips, and chemical separations. Usually, electrical impedance tomography (EIT) is visualized, into a cross-sectional image representing the distribution of density. BIT is recently developed imaging technique, with which images of the conductivity or permittivity of the subject can be rapidly collected with channels of external electrodes. Therefore, we considered application of BIT to the microchannels. In this paper, we develop the EIT for microchannel nano particles concentration in microchannel with 60 multi-layer electrodes and measured using cross-sectional impedance measurement technique. Based on the reconstructed image using the BIT system and analytical calculation using Maxwell equation, we discuss the initial concentration condition effect and the stream transitional migration to estimate particle migration behaviors in the fluid flow. The measured results shows up to 24% particles moved from upstream to downstream cross-section, where the particles move away from center streamlines to near wall vicinity area and the number of the particles migration towards wall vicinity area is clearly increased near the outlet area. The stream transitional particle migration due to inertia lift forces is investigated with the effect of the initial particle concentration.

This paper simulates the electrical particle concentration and migration in the small diameter particles in a micro-channel using CFD. This research is a first step to visualize, concentrate and distribute particles behavior at certain cross-section and between cross section under capacitance sensing. The calculation conditions are Reynolds number influence of electrical power, and cross-section, AC, and frequency. To obtain the high quantitative information of two-phase flow, use Clausius-Mossotti theory, Navier-Stokes and Maxwell equations. As a result, particle is moved in the case of cross-sections. The result is very useful for developing a detector of thrombus in an artificial heart.

Monitoring the flow behaviour on the micro-scale is very important in many industrial and biochemical process, the multiphase coexistence in microchannel provide many attractive characteristics compared to a single-phase flow. The precise flow rate control and well-defined channel geometries make it possible for us to make detailed investigation on multiphase flow phenomena. This paper aims at the measurement of resistance distribution in the cross-section of a novel microchannel based on the Agilent measuring instruments. Experimental results verified the possibility of estimation on particle concentration in the solid-liquid two-phase flow by the measurement of resistance distribution in the microchannel.

Monitoring of thrombogenic process is very important in ventricular assistance devices (VADs) used as temporary or permanent measures in patients with advanced heart failure. Currently, there is a lack of a system which can perform a real-time monitoring of thrombogenic activity. Electrical signals vary according to the change in concentration of coagulation factors as well as the distribution of blood cells, and thus have potential to detect the thrombogenic process in an early stage. In the present work, we have made an assessment of an instrumentation system exploiting the electrical properties of blood. The experiments were conducted using bovine blood. Electrical resistance tomography with eight-electrode sensor was used to monitor the spatio-temporal change in electrical resistivity of blood in thrombogenic and non-thrombogenic condition. Under non-thrombogenic condition, the resistivity was uniform across the cross-section and average resistivity monotonically decreased with time before remaining almost flat. In contrary, under thrombogenic condition, there was non-uniform distribution across the cross-section, and average resistivity fluctuated with time.

In a present study, capacitance sensing is used as a visualization method for determination of dielectric permittivity distribution in microchannel system from external capacitance measurement. The microchannel had fabricated using micro-electro-mechanical-systems (MEMS) advanced technology which has two inlets and outlets and five cross-sections that each cross-section was embedding with 12 electrodes pair that connected to the microchannel system. The capacitance sensing had measured at cross-section III and V at different condition of inlets injection which cross-section III is located at the center of microchannel while cross-section V is nears the outlets. The dynamic behaviors of 6.0μm of polystyrene particles and deionized water are investigated by using capacitance sensing and particles concentration distribution in a presence of non-uniform electric fields of micro electrodes are studied in details. The permittivity and concentration of particles in term of a particle volume fraction are calculated at different zone of the microchannel area measurement. The microchannel area measurement are divided into three different zones which zone I is a measurement near a wall, zone II is a measurement halfway between centerlines and the wall and zone III is a measurement at the centerlines of microchannel system. The particles are more concentrate in zone I and zone II which is the area between centerlines of microchannel and near the wall that indicates a migration of particles are happen in the microchannel that seems to be reflect to the Serge-Silberberg phenomenon. © 2011 IEEE.

In this study, a cross-sectional capacitance is measured in a microchannel with 12 multi-layered electrodes. The cross-sectional capacitance of polystyrene particles and deionized water is measured at upstream and downstream microchannel. Based on the measured cross-sectional capacitance, the particle volume fraction is calculated at three area measurements with different electrode pair. The three area measurements are at the adjacent pair, horizontal pair and vertical pair. The particle volume fraction at the adjacent pair area is almost same and higher at upstream and downstream cross-section. While at the vertical and horizontal pair areas, the particle volume fraction increased from upstream to downstream cross-section around 1.0-9.3% at electrode pair near the walls whilst decreased 0.4-0.96% at electrode pair near the center streamlines. It shows the particles are more attracted to migrate to the equilibrium position at near to the walls. The particles migration induced by inertial lift forces is reflected to Serge-Silberberg phenomenon where the particles are distributed and transverse from the center streamlines of fluid flowing to the area near the walls.

Revealing gas-liquid permeable flow phenomena in the porous media is helpful for the environmental impact assessment of geological disposal of radioactive waste and purification of radioactive contamination water. This paper aims to investigate the liquid phase dispersion inside co-current downward gas-liquid flow in the bed packed with spherical particle as basic model. Water and air are injected from the top center of column, and water is spreading to the entire cross-section flowing down along the column. Radial dispersion of water is captured by electrical resistance tomography on several axial positions. The results indicated that liquid flow rate have impact on radial dispersion of water.

This paper shows a result of simulations of the particle behavior at particle-liquid two phase flow via dielectrophoresis varied the number of electrodes by using COMSOL. Dielectrophoresis is very important technique to study tomography at micro-scale. The calculation parameters are Reynolds number, voltage and volume fraction, Particles volume fraction is the same in the each cases. As a result, the particle behavior and capacitance are changed by the case of electrode number and distance. This calculation result is very useful for developing a tomography conditions.

The present study describes the electrical tomography sensing and dielectrophoresis (DEP) force for visualize the 3D particle mixing in the microchannel system. In the presence of non-uniform electric fields generated by point microelectrodes, the dynamic distribution behaviors of a polystyrene particle and deionized water had been investigated in this system. Microchannel was fabricated with five cross sections where 12 electrodes were installed for each measurement plane. In this experiment, the relationship between electric field frequency and DEP force of particles are calculated at different electric frequencies and diameter of particles. The applied electric field intensities are E=+/- 1 V/mm, +/- 3 V/mm and +/- 5 V/mm while the electric field frequencies are f=1 kHz, 10 kHz, 100 kHz and 1 MHz and the diameter of particles are 1.3 mu m, 1.5 mu m and 2.0 mu m are investigated in this experiment. Simultaneously, imaged by manipulating tomography sensing at cross section A, C and D and the coupled DEP forces at cross section B and D, the particles flowing had been visualized and concentrate uniformly at near the outlets. The electrical capacitances and DEP forces between the electrode pairs of the microchannel were measured and the ECT tomograms representing the particle distribution were constructed from the measured capacitance data for each cross section in microchannel.

Impedance spectroscopy (IS) is a measure of the electrical response of a system, and analysis of the response to yield useful information about the different properties of the system. In the present work, its application for the determination of concentration of the particles in the flowing liquid is presented. Experimental results are presented for polysterine particles floated in the water. Additionally, the method has potential to determine the composition of the liquid. Experimental results with the mixture of milk and yougurt are presented. Moreover, simulation results with the blood cells floating in the suspending plasma are presented to study the application of the methodology to monitor the clotting of the blood.

In the present paper, the extraction of dominant particle concentration fluctuation at various time space frequency levels from reconstructed electrical capacitance tomography (ECT) images by means of the discrete wavelet transform has been proposed. Using this concept, three-dimensional images (time and two-dimensional space) obtained by an ECT system are decomposed into different time and space levels to characterize the intrinsic features of the particle distribution in a down-flow fluidized bed with a newly designed distributor using three-dimensional discrete wavelet multiresolution. As a result, the dominant time and space particle distribution characteristics for a specific frequency level can be visualized. On the basis of the wavelet analysis results, the best operation condition, under which the most stable and uniform particle distribution can be obtained, was clarified. This provides a good reference for the optimization of a downer reactor to qualify the refinery process in the petroleum industry. (C) 2011 Elsevier B.V. All rights reserved.

PTV (Particle Tracking Velocimetry) has been limitedly used for the measurements of flow fields because there have been interpolation data loss which is inevitable to PTV in principle. In this paper, a hybrid PTV algorithm which eliminates interpolation data losses has been constructed by using an affine transformation. In order to evaluate the performances of the constructed hybrid PIV algorithm, an artificial image test was made using the Green-Taylor vortex data. The constructed algorithm was tested on the experimental images of the wake flow(Re=5, 300) of a rectangular body(6cm × 3cm), through which its excellence was demonstrated. Copyright © 2011 by ASME.

The three dimensional cross-sectional particle concentrations of particle-liquid two phase flows in the two cross-seciton of microchannel has been reconstructed using process tomography. In the obtained 3D (2D space and time) reconstruction image, the dielectric particle-injected area appears to have a high particle concentration, and the deionized water-injected area appears to have a low particle concentration. Dielectric particles as the solid phase and non-conductive deionized water as the liquid phase are non-uniformly injected to the microchannel. The comparison between the qualitative result of 3D reconstruction image and the quantitative result of particle concentration in flow direction transition is that the particle is reasonably distributed in the particle injected area of the cross-section. Based on the reconstructed particle distribution image, it is easy to estimate the particle diffusion behaviors in microchannel. Copyright © 2011 by ASME.

Phase-based methods of active thermographic studies provide deeper subsurface details and reduce non-uniform emissivity problems in defect detection. In this contribution analysis of subsurface anomalies has been carried out by probing a suitable frequency component with sufficient energy. This paper highlights the comparative analysis of different thermographic schemes on the basis of supplying equal energy to the chosen frequency used for the analysis of a given carbon fiber-reinforced plastic sample used in experimentation. Experiments have been carried out to find the detection ability of different excitation schemes, and comparisons have been made by taking the signal-to-noise ratio of the defects into consideration. © 2011 IOP Publishing Ltd.

The application of micro process tomography to microchannels is considered in this paper. Using the micro process tomography system in microchannel, a particle distribution image can be obtained in a two phase flow. Based on the reconstructed image, it is easy to estimate the particle movement in a fluid flow. A novel microchannel system is designed for electrical process tomography that includes 60 electrodes distributed cross-sectional at five positions. The particle and water were injected into the microchannel, and then the capacitance of the fluid flow was measured at cross-section of microchannel. The result showed the 2D image of particle distribution of cross-section in the microchannel. Also, cross-sectional images of the particle distribution of a two phase flow are simulated.

A numerical study on flow and heat transfer of de-ionized water over in-line and staggered micro-cylinder-groups had been performed with Reynolds number varying in the range from 0 to 150. A 3-D incompressible numerical model was employed to investigate the vortex distributions and the influences of the vortexes on the flow and heat transfer characteristics at low Re numbers in micro-cylinder-groups with different geometrical parameters, including micro-cylinder diameters (100 mu m, 250 mu m and 500 mu m), ratios of pitch to micro-cylinder diameter (1.5 2 and 2.5) and ratios of microcylinder height to diameter (0.5, 1, 1.5 and 2), etc. The vortex distributions, the flow and temperature fields, and the relationships among them were investigated by solving the numerical model with the finite volume method. It was found that the vortex number became larger with the increase of pitch ratio, and the change of flow rate distribution affected the heat transfer characteristics apparently. The appearance of vortexes in micro-cylinder-group increased the differential pressure resistance; as a result the total flow resistance in micro-cylinder-groups correspondingly increased. Meanwhile, the local heat transfer coefficients nearby the locations of vortexes greatly increased due to the boundary layer separation, which further enhanced the heat transfer in micro-cylinder-groups. The new correlations which could predict Nusselt number of de-ionized water over micro-cylinders with Re number varying from 0-150 had been proposed considering the differential pressure resistance and the natural convection based on numerical calculations in this paper.

This paper presents a numerical study of the particle behaviors under acceleration conditions in the solid-air two-phase flow by means of a combined two-dimensional model of computational fluid dynamics and discrete element method (CFD-DEM). The simulation model provides the information regarding the particle distribution behaviors within the calculation region and the particle run-out rate from the calculation region under different parameter conditions, such as particle size, initial particle loading and particle acceleration condition. The results demonstrate that the particle run-out rate is directly influenced by the particle size and the initial loading condition. The particle acceleration in the horizontal direction adversely affects the particle run-out rate when the initial particle loading condition is dispersed and uniform. However, this adverse effect disappears when the initial particle loading condition becomes concentrate and partial.

A three-dimensional numerical model of the down-flow fluidized bed (Downer) with a newly designed distributor was applied to investigate the particle distribution profiles using combined computational fluid dynamics (CFD) and the discrete element method (DEM). A realistic model of DEM, which calculates the contact force acting on the individual particles, is used to monitor the movement of individual particles in the bed. The contact force is calculated using the concepts of the spring, dash-pot, and friction slider. The flow field of gas is predicted by the Navier-Stokes equation. This CFD-DEM model provides information regarding the particle movement and distribution, the particle velocity, and the gas velocity in the bed under different air-particle mixture conditions. The results demonstrate that the air supply conditions directly influence the particle distribution uniformity. Furthermore, the numerical predictions for the axial and radial profiles of the particle distribution were found to agree well with the experimental results obtained by electrical capacitance tomography (ECT). (C) 2010 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.

In the present study, a combined model of computational fluid dynamics and the discrete element method (CFD-DEM) was used to simulate the particle distributions in a down-flow fluidized bed (DFB) with a newly designed particle-air distributor. In the simulation model, particle motion is calculated by solving Newton&apos;s equations and the flow field of air is predicted by the Navier-Stokes equations. The calculation was made for the same geometric and operating conditions as the experiment which was carried out for comparison with the simulation using electrical capacitance tomography (ECT). The numerical predictions for the axial and radial profiles of the particle distribution agreed well with the experimental results. (C) 2010 Elsevier Ltd. All rights reserved.

The present study describes the fabrication of a novel microchannel with 60 electrodes and the electrical resistance measurement in different flow types in the microchannel system. This microchannel is designed for ERT application, which has five measurement cross sections and embeds 12 electrodes in each cross section. The microchannel has been successfully fabricated by MEMS processes which are comprised of photolithography of platinum wire on quartz glass layers, compression to fabricate the electrode layers, and micro mechanical processing for the flow groove. After the microchannel fabrication, the connector is constructed in order to avoid unstable measurement condition between the microchannel electrodes and the resistance measurement system. The electrical resistances between the electrode pairs of the microchannel were measured in the case of tap water, particle flow and the separately injected tap water plus particle flow. The electrical resistances are reasonably and stably measured in the microchannel. (C) 2010 Elsevier Ltd. All rights reserved.

The three-dimensional flow characteristics of a new hybrid vertical axis wind turbine have been investigated by conditional sampling stereoscopic PIV^* in order to clarify the three-dimensional motions of the upper surface flow at the edge of the turbine blade which is moving perpendicularly to the flow. The experimental apparatus is constructed using the PIV measurement system with a conditional sampling device and a new hybrid vertical axis wind turbine installed in a circulating water channel.

This study is a first step in developing a three-dimensional separation and classification system in a minichannel in which 60 electrodes are embedded in a three-dimensional arrangement. Particle velocities driven by the dielectrophoresis (DEP) force are measured in a simplified minichannel with electric field intensities from E=&plusmn;1 V/mm to &plusmn;5 V/mm, electric field frequencies from &fnof;=1 kHz to &fnof;=1 MHz, and particles with diameter of d=1.3 &mu;m, 1.5 &mu;m and 2.0 &mu;m. Both the DEP force and the particle velocities increase as the particle diameter increases. In addition, particles have higher velocities when higherelectric field intensities are applied.<BR>Electrodes two dimensional are used for DEP in the research of the past. Moreover, the plane electrode of the wedge place is used to generate DEP positively. The possibility of a three dimensional operation was confirmed by using the parallel plate electrode array in this research.

&nbsp;&nbsp;The present paper introduces a numerical study of the particle behaviors under acceleration conditions in the solid-air two-phase flow by means of a combined two-dimensional model of computational fluid dynamics and the discrete element method (CFD-DEM). The simulation model provides information regarding the particle distribution behaviors within the calculation region and the particle run-out rate from the calculation region under different parameter conditions, such as particle size, initial particle loading and particle acceleration condition. The results demonstrate that the particle run-out rate is directly affected by the particle size and the initial loading condition. The particle acceleration in the horizontal direction adversely affects the particle run-out rate when the initial particle loading condition is dispersed and uniform. However, this adverse effect disappears when the initial particle loading condition becomes concentrated and partial.

&nbsp;&nbsp;This paper has launched a concept of tomographic resistivity distribution measurement in a microchannel for a heat exchanger. With the concept, cross-sectional images of assumed resistivity distribution due to micro bubble in an electrical resistance tomography (ERT) has been simulated by using algorithms of forward and inverse problems. The first step of the algorithm is a forward problem; namely, it is to calculate an electrical potential on electrodes from the assumed resistivity distribution by solving the Maxwell equation. The second step of the algorithm is an inverse problem; namely, it is to calculate the resistivity distribution from the electrical potential on the electrodes calculated by the forward problem. In order to discuss the concept availability in the inverted annular flow and the stratified flow, the simulation results show that the flow condition depends on the correlation. Especially, the stratified flow has a high correlation coefficient as compared to the inverted annular flow.

In the present study, cross-sectional images of the assumed particle distribution of a particle-liquid two-phase flow are simulated using a newly proposed algorithm and electrical resistance tomography (ERT) with four current patterns. The first step of the algorithm is a forward problem, which involves calculating the electrical potential on electrodes from the assumed particle distribution by solving the Maxwell equation. The second step of the algorithm is an inverse problem, which involves calculating the particle distribution from the electrical voltage calculated by the forward problem. In the simulation conditions of the four current patterns, namely, opposite, adjacent, one-reference, and trigonometric methods are used to discuss the most accurate current patterns in three types of particle-liquid two-phase flow, namely, annular, stratified, and dispersed flows. The simulation results reveal that the current pattern depends on the flow conditions. In particular, among the four current patterns, the trigonometric method is found to be preferable.

An Electrical Capacitance Tomography (ECT) system has been applied to non-invasively visualize the solid distribution in a downflow fluidized bed (downer) with a specially designed distributor. By means of this distributor, air can be supplied from both the axial and radial directions. In order to understand its effect on the solid distribution, the solid concentration characteristic was discussed in both the time and space domains. As a result, the specially designed distributor leads to a more uniform solid distribution near the entrance region. As the measurement position descends, the solid distribution becomes uniform. The solid concentration increases as the center-side airflow rate ratio varies from 1:4 to 1:1. Moreover, the air velocity in the axial direction adversely affects the temporal stability of solid concentration, whereas the air velocity in radial direction contributes significantly to the spatial uniformity. (C) 2009 Elsevier B.V. All rights reserved.

Increased demand for greater sub­surface probing in InfraRed Non­Destructive Testing (IRNDT), for subsurface sensing is often thwarted by the requirement of high speed IR cameras and very high peak power heat sources. Present approach highlights subsurface exploration based on pulse compression approach. This offers a means of increasing average power available to illuminate test specimen without any loss of the depth resolution needed for the tactical requirements. This is accomplished by transmitting a long duration pulse, in which the incident heat flux is frequency modulated and then, by adopting correlation based method on the captured temporal data. This leads to a time compression of the received signal to a much narrower pulse of high effective peak power. For the demonstration, a mild steel sample having flat bottom holes at various depths is introduced. And detection capability of the proposed correlation based approach has been studied, by considering the full width at half power points of the compressed pulses, from various defects.

The application of process computed tomography to microchannels is considered in this paper. Using the process computed tomography system in microchannel, a particle distribution image can be obtained in a multiphase flow. Based on the reconstructed image, it is easy to estimate the particle diffusion behaviors in a fluid flow. A microchannel system is designed for process computed tomography, the fabrication of a microchannel with 80 electrodes and the measured impedance of an electrode in the microchannel. The manufacturing process for the microchannel is successfully completed by compressing two quartz glass layers with a platinum electrode. The sub-microparticle distribution was measured in the cross-section of microchannel by using micro process tomography. The sub-microparticle distribution is changed to the time. Usually the sub-microparticle is distributed in the center of cross-section. A numerical simulation for the sub-microparticle distribution was performed by combining the discrete element method and computational fluid dynamics in a three-dimensional domain. Distribution images of the sub-microparticle were obtained by the simulation. The sub- microparticles move toward the outlet area and leave the container through the outlet, although some of the sub-microparticles concentrate at the center side.

This paper presents a study of the particle dispersion behaviours under acceleration conditions in the solidair twophase flow by means of a combined threedimensional model of computational fluid dynamics and discrete element method (CFDDEM). The simulation model provides the information regarding the particle distribution behaviours within the calculation region and the particle runout rate from the calculation region under different parameter conditions, such as particle size, initial particle loading and particle acceleration condition. The calculation was made for the same geometric and operating conditions as the experiment which was carried out for comparison with the simulation using laser tomography. The comparison results demonstrate that the acceleration in the horizontal direction adversely affects the particle runout rate.

The application of process computed tomography to microchannels is considered in this paper. Using the process computed tomography system in microchannel, a particle distribution image can be obtained in a multiphase flow. Based on the reconstructed image, it is easy to estimate the particle diffusion behaviors in a fluid flow. A microchannel system is designed for process computed tomography. The particle and water were injected into the microchannel, and then the capacitance of the fluid flow was measured at the cross-section. The particle distribution of cross-section is estimated in the micro channel. Especially, it has been reconstructed that the 3-D image of particle distribution. Also, cross-sectional images of the particle distribution of a two phase flow are compared to results obtained from computer simulations. ©2010 IEEE.

Nucleate pool boiling heat transfer in microcapillary grooves with different microcavity distribution is investigated experimentally. Using de-ionized water as a working fluid, the influence of the diameters and distributions of the microcavities on the nucleate pool boiling heat transfer characteristics of a microcapillary-grooved plate are obtained at different liquid levels in an evaporator. The investigations show that the existence of cavities apparently increases the bubble numbers on the surfaces of the microcapillary grooves, especially for the cavities with smaller diameters. However, the existence of the cavities also increase the flow resistance of the liquid driven by the capillary force in the microcapillary grooves. The optimum distance between the neighboring cavities is about 3.1 times the diameter of the cavity. The boiling heat transfer coefficients of the microcapillary grooves with the structured surfaces of the cavities are compared with the predictions of experimental correlation for conventional microcapillary grooves. The results indicate that the nucleate boiling heat transfer in microcapillary grooves is much enhanced by manufacturing microcavities on the surfaces, and the boiling heat transfer coefficients of the microcapillary grooves with microcavities of L/D = 3.1 is about five times higher than those predicted by the correlation of convective boiling heat transfer.

Ultrasonic has been applied to dense-phase low-speed transportation, called plug transportation, in horizontal pipes, and the friction reduction effect has been investigated by using four types of particles in a pipe 50 mm in diameter. In this paper, it was confirmed that the friction between the particles and pipe wall and the pressure drop are reduced as the application of ultrasonic increases. It was also shown that this reduction effect becomes small as the air mass flow rate becomes large, and the friction reduction can be predicted calculably. Additionally, in order to apply ultrasonic for pipelines, the connection method of a vibration pipe that can prevent air leakage and does not reduce the amplitude of the vibration pipe, was proposed. As a result, this method can be applied for pipe pressures under 56 kPa.

Capacitance computed tomography techniques were used to visualize particles movement in the draft tube of a spouted fluidized bed for the coating process of drug production. A total of 512 frames images of the particle concentration distribution were obtained at 10-millisecond intervals over a coating time of 5 min using a capacitance computed tomography system. The three-dimensional capacitance CT images (time and two-dimensional space images) were decomposed to wavelet time and space levels to extract the dominant particle distribution feature using three-dimensional discrete wavelet multiresolution at different coating times. As a result, the time and space dominant particle distribution with a specific frequency level can be visualized. (C) 2009 Elsevier B.V. All rights reserved.